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.TH CPG_INITIALIZE 3 2019-04-16 "corosync Man Page" "Corosync Cluster Engine Programmer's Manual"
.SH NAME
cpg_initialize \- Create a new connection to the CPG service
.SH SYNOPSIS
.B #include <corosync/cpg.h>
.sp
.BI "int cpg_initialize(cpg_handle_t *" handle ", cpg_callbacks_t *" callbacks ");
.SH DESCRIPTION
The
.B cpg_initialize
function is used to initialize a connection to the closed process groups API. This function is deprecated
and
.B cpg_model_initialize
should be used in newly written code.
.PP
Each application may have several connections to the CPG API.  Each application
uses the
.I handle
argument to uniquely identify the connection.  The
.I handle
argument is then used in other function calls to identify the connection to be used
for communication with the CPG service.
.PP
Every time an CPG event occurs within the joined group, one of the callbacks specified by the argument
.I callbacks
is called.  The callback functions are described by the following type definitions:
.PP
.PP
.IP
.RS
.ne 18
.nf
.ta 4n 20n 32n

typedef void (*cpg_deliver_fn_t) (
        cpg_handle_t handle,
        const struct cpg_name *group_name,
        uint32_t nodeid,
        uint32_t pid,
        const void *msg,
        size_t msg_len);


typedef void (*cpg_confchg_fn_t) (
        cpg_handle_t handle,
        const struct cpg_name *group_name,
        const struct cpg_address *member_list, size_t member_list_entries,
        const struct cpg_address *left_list, size_t left_list_entries,
        const struct cpg_address *joined_list, size_t joined_list_entries);

.ta
.fi
.RE
.IP
.PP
.PP
The
.I callbacks
argument is of the type:
.IP
.RS
.ne 18
.nf
.PP
typedef struct {
        cpg_deliver_fn_t cpg_deliver_fn;
        cpg_confchg_fn_t cpg_confchg_fn;
} cpg_callbacks_t;
.ta
.fi
.RE
.IP
.PP
When a configuration change occurs or a message is to be delivered one of the callbacks
is called from the
.B cpg_dispatch()
function.  If a configuration change occurs,
.I cpg_confchg_fn
is called.  If a delivery of a message occurs,
.I cpg_deliver_fn
is called.

The
.I cpg_address
structure is defined
.IP
.RS
.ne 18
.nf
.PP
struct cpg_address {
        unsigned int nodeid;
        unsigned int pid;
        unsigned int reason;
};
.ta
.fi
.RE
.IP
.PP
where nodeid is a 32 bit unique node identifier, pid is the process ID of the process that has joined/left the group
or sent the message, and reason is an integer code indicating why the node joined/left the group (this value is not
set for the member_list items).
.PP
.IP
.RS
.ne 18
.nf
.PP
CPG_REASON_JOIN      - the process joined a group using cpg_join().
CPG_REASON_LEAVE     - the process left a group using cpg_leave()
CPG_REASON_NODEDOWN  - the process left a group because the node left the cluster.
CPG_REASON_NODEUP    - the process joined a group because it was already a member of a group on a node that has just joined the cluster
CPG_REASON_PROCDOWN  - the process left a group without calling cpg_leave()
CPG_REASON_UNDEFINED - a special value used for the member_list items
.ta
.fi
.RE
.IP
.PP
.SH RETURN VALUE
This call returns the CS_OK value if successful, otherwise an error is returned.
.PP
.SH ERRORS
The errors are undocumented.
.SH "SEE ALSO"
.BR cpg_overview (3),
.BR cpg_initialize (3),
.BR cpg_finalize (3),
.BR cpg_fd_get (3),
.BR cpg_dispatch (3),
.BR cpg_join (3),
.BR cpg_leave (3),
.BR cpg_mcast_joined (3),
.BR cpg_membership_get (3)
.BR cpg_zcb_alloc (3)
.BR cpg_zcb_free (3)
.BR cpg_zcb_mcast_joined (3)
.BR cpg_context_get (3)
.BR cpg_context_set (3)
.BR cpg_local_get (3)
.BR cpg_model_initialize (3)

.PP
